RST reader: improve parsing of inline interpreted text roles.

* Use a Span with class "title-reference" for the default
  title-reference role.
* Use B.text to split up contents into Spaces, SoftBreaks, and Strs
  for title-reference.
* Use Code with class "interpreted-text" instead of Span and Str for
  unknown roles.  (The RST writer has also been modified to round-trip
  this properly.)
* Disallow blank lines in interpreted text.
* Backslash-escape now works in interpreted text.
* Backticks followed by alphanumerics no longer end interpreted text.

Closes #4811.

6 files changed, 86 insertions, 19 deletions

diff --git a/src/Text/Pandoc/Readers/RST.hs b/src/Text/Pandoc/Readers/RST.hs
index f9752a83c..576c3b77c 100644
--- a/src/Text/Pandoc/Readers/RST.hs
+++ b/src/Text/Pandoc/Readers/RST.hs
@@ -37,7 +37,7 @@ import Control.Arrow (second)
 import Control.Monad (forM_, guard, liftM, mplus, mzero, when)
 import Control.Monad.Except (throwError)
 import Control.Monad.Identity (Identity (..))
-import Data.Char (isHexDigit, isSpace, toLower, toUpper)
+import Data.Char (isHexDigit, isSpace, toLower, toUpper, isAlphaNum)
 import Data.List (deleteFirstsBy, elemIndex, intercalate, isInfixOf, isSuffixOf,
                   nub, sort, transpose, union)
 import qualified Data.Map as M
@@ -1385,7 +1385,6 @@ strong = B.strong . trimInlines . mconcat <$>
 --
 -- TODO:
 --  - Classes are silently discarded in addNewRole
---  - Lacks sensible implementation for title-reference (which is the default)
 --  - Allows direct use of the :raw: role, rST only allows inherited use.
 interpretedRole :: PandocMonad m => RSTParser m Inlines
 interpretedRole = try $ do
@@ -1395,12 +1394,12 @@ interpretedRole = try $ do
 renderRole :: PandocMonad m
            => String -> Maybe String -> String -> Attr -> RSTParser m Inlines
 renderRole contents fmt role attr = case role of
-    "sup"  -> return $ B.superscript $ B.str contents
-    "superscript" -> return $ B.superscript $ B.str contents
-    "sub"  -> return $ B.subscript $ B.str contents
-    "subscript"  -> return $ B.subscript $ B.str contents
-    "emphasis" -> return $ B.emph $ B.str contents
-    "strong" -> return $ B.strong $ B.str contents
+    "sup"  -> return $ B.superscript $ treatAsText contents
+    "superscript" -> return $ B.superscript $ treatAsText contents
+    "sub"  -> return $ B.subscript $ treatAsText contents
+    "subscript"  -> return $ B.subscript $ treatAsText contents
+    "emphasis" -> return $ B.emph $ treatAsText contents
+    "strong" -> return $ B.strong $ treatAsText contents
     "rfc-reference" -> return $ rfcLink contents
     "RFC" -> return $ rfcLink contents
     "pep-reference" -> return $ pepLink contents
@@ -1411,7 +1410,7 @@ renderRole contents fmt role attr = case role of
     "title" -> titleRef contents
     "t" -> titleRef contents
     "code" -> return $ B.codeWith (addClass "sourceCode" attr) contents
-    "span" -> return $ B.spanWith attr $ B.str contents
+    "span" -> return $ B.spanWith attr $ treatAsText contents
     "raw" -> return $ B.rawInline (fromMaybe "" fmt) contents
     custom -> do
         customRoles <- stateRstCustomRoles <$> getState
@@ -1419,14 +1418,20 @@ renderRole contents fmt role attr = case role of
             Just (newRole, newFmt, newAttr) ->
                 renderRole contents newFmt newRole newAttr
             Nothing -> -- undefined role
-                return $ B.spanWith ("",[],[("role",role)]) (B.str contents)
+                return $ B.codeWith ("",["interpreted-text"],[("role",role)])
+                          contents
  where
-   titleRef ref = return $ B.str ref -- FIXME: Not a sensible behaviour
+   titleRef ref = return $ B.spanWith ("",["title-ref"],[]) $ treatAsText ref
    rfcLink rfcNo = B.link rfcUrl ("RFC " ++ rfcNo) $ B.str ("RFC " ++ rfcNo)
      where rfcUrl = "http://www.faqs.org/rfcs/rfc" ++ rfcNo ++ ".html"
    pepLink pepNo = B.link pepUrl ("PEP " ++ pepNo) $ B.str ("PEP " ++ pepNo)
      where padNo = replicate (4 - length pepNo) '0' ++ pepNo
            pepUrl = "http://www.python.org/dev/peps/pep-" ++ padNo ++ "/"
+   treatAsText = B.text . handleEscapes
+   handleEscapes [] = []
+   handleEscapes ('\\':' ':cs) = handleEscapes cs
+   handleEscapes ('\\':c:cs) = c : handleEscapes cs
+   handleEscapes (c:cs) = c : handleEscapes cs
 
 addClass :: String -> Attr -> Attr
 addClass c (ident, classes, keyValues) = (ident, classes `union` [c], keyValues)
@@ -1450,7 +1455,18 @@ roleAfter = try $ do
   return (role,contents)
 
 unmarkedInterpretedText :: PandocMonad m => RSTParser m [Char]
-unmarkedInterpretedText = enclosed (atStart $ char '`') (char '`') anyChar
+unmarkedInterpretedText = try $ do
+  atStart (char '`')
+  contents <- mconcat <$> (many1
+       (  many1 (noneOf "`\\\n")
+      <|> (char '\\' >> ((\c -> ['\\',c]) <$> noneOf "\n"))
+      <|> (string "\n" <* notFollowedBy blankline)
+      <|> try (string "`" <*
+                notFollowedBy (() <$ roleMarker) <*
+                lookAhead (satisfy isAlphaNum))
+       ))
+  char '`'
+  return contents
 
 whitespace :: PandocMonad m => RSTParser m Inlines
 whitespace = B.space <$ skipMany1 spaceChar <?> "whitespace"
diff --git a/src/Text/Pandoc/Writers/RST.hs b/src/Text/Pandoc/Writers/RST.hs
index f355a8f5b..566bcbeef 100644
--- a/src/Text/Pandoc/Writers/RST.hs
+++ b/src/Text/Pandoc/Writers/RST.hs
@@ -574,15 +574,18 @@ inlineToRST (Quoted DoubleQuote lst) = do
      else return $ "“" <> contents <> "”"
 inlineToRST (Cite _  lst) =
   writeInlines lst
+inlineToRST (Code (_,["interpreted-text"],[("role",role)]) str) = do
+  return $ ":" <> text role <> ":`" <> text str <> "`"
 inlineToRST (Code _ str) = do
   opts <- gets stOptions
   -- we trim the string because the delimiters must adjoin a
   -- non-space character; see #3496
   -- we use :literal: when the code contains backticks, since
   -- :literal: allows backslash-escapes; see #3974
-  return $ if '`' `elem` str
-              then ":literal:`" <> text (escapeString opts (trim str)) <> "`"
-              else "``" <> text (trim str) <> "``"
+  return $
+    if '`' `elem` str
+       then ":literal:`" <> text (escapeString opts (trim str)) <> "`"
+       else "``" <> text (trim str) <> "``"
 inlineToRST (Str str) = do
   opts <- gets stOptions
   return $ text $
diff --git a/test/Tests/Readers/RST.hs b/test/Tests/Readers/RST.hs
index 540c5d45a..8916eed6f 100644
--- a/test/Tests/Readers/RST.hs
+++ b/test/Tests/Readers/RST.hs
@@ -177,7 +177,7 @@ tests = [ "line block with blank line" =:
             =: ".. role:: haskell(code)\n.. role:: lhs(haskell)\n\n:lhs:`text`"
             =?> para (codeWith ("", ["lhs", "haskell", "sourceCode"], []) "text")
           , "unknown role" =: ":unknown:`text`" =?>
-              para (spanWith ("",[],[("role","unknown")]) (str "text"))
+              para (codeWith ("",["interpreted-text"],[("role","unknown")]) "text")
           ]
         , testGroup "footnotes"
           [ "remove space before note" =: T.unlines
diff --git a/test/command/3407.md b/test/command/3407.md
index 3160d1263..aec253ff5 100644
--- a/test/command/3407.md
+++ b/test/command/3407.md
@@ -1,6 +1,6 @@
 ```
 % pandoc -f native -t rst
-[Para [Span ("",[],[("role","foo")]) [Str "text"]]]
+[Para [Code ("",["interpreted-text"],[("role","foo")]) "text"]]
 ^D
 :foo:`text`
 ```
@@ -9,5 +9,5 @@
 % pandoc -f rst -t native
 :foo:`text`
 ^D
-[Para [Span ("",[],[("role","foo")]) [Str "text"]]]
+[Para [Code ("",["interpreted-text"],[("role","foo")]) "text"]]
 ```
diff --git a/test/command/4811.md b/test/command/4811.md
new file mode 100644
index 000000000..9c8bea7ce
--- /dev/null
+++ b/test/command/4811.md
@@ -0,0 +1,48 @@
+No blank lines in inline interpreted roles:
+
+```
+% pandoc -f rst -t native
+`no
+
+blank`:myrole:
+^D
+[Para [Str "`no"]
+,Para [Str "blank`:myrole:"]]
+```
+
+Backslash escape behaves properly in interpreted roles:
+
+```
+% pandoc -f rst -t native
+`hi\ there`:sup:
+
+`hi\ there`:code:
+^D
+[Para [Superscript [Str "hithere"]]
+,Para [Code ("",["sourceCode"],[]) "hi\\ there"]]
+```
+
+Backtick followed by alphanumeric doesn't end the span:
+```
+% pandoc -f rst -t native
+`hi`there`:myrole:
+^D
+[Para [Code ("",["interpreted-text"],[("role","myrole")]) "hi`there"]]
+```
+
+Newline is okay, as long as not blank:
+```
+% pandoc -f rst -t native
+`hi
+there`:myrole:
+^D
+[Para [Code ("",["interpreted-text"],[("role","myrole")]) "hi\nthere"]]
+```
+
+Use span for title-reference:
+```
+% pandoc -f rst -t native
+`default`
+^D
+[Para [Span ("",["title-ref"],[]) [Str "default"]]]
+```
diff --git a/test/rst-reader.native b/test/rst-reader.native
index b0e51bd3f..89dde7396 100644
--- a/test/rst-reader.native
+++ b/test/rst-reader.native
@@ -326,7 +326,7 @@ Pandoc (Meta {unMeta = fromList [("author",MetaList [MetaInlines [Str "John",Spa
 ,Para [Math DisplayMath "\\alpha = beta",Math DisplayMath "E = mc^2"]
 ,Para [Str "Some",Space,Superscript [Str "of"],Space,Str "these",Space,Superscript [Str "words"],Space,Str "are",Space,Str "in",Space,Superscript [Str "superscript"],Str "."]
 ,Para [Str "Reset",Space,Str "default-role",Space,Str "to",Space,Str "the",Space,Str "default",Space,Str "default."]
-,Para [Str "And",Space,Str "now",Space,Str "some-invalid-string-3231231",Space,Str "is",Space,Str "nonsense."]
+,Para [Str "And",Space,Str "now",Space,Span ("",["title-ref"],[]) [Str "some-invalid-string-3231231"],Space,Str "is",Space,Str "nonsense."]
 ,Para [Str "And",Space,Str "now",Space,Str "with",Space,RawInline (Format "html") "<b>inline</b> <span id=\"test\">HTML</span>",Str "."]
 ,Para [Str "And",Space,Str "some",Space,Str "inline",Space,Str "haskell",Space,Code ("",["haskell","sourceCode"],[]) "fmap id [1,2..10]",Str "."]
 ,Para [Str "Indirect",Space,Str "python",Space,Str "role",Space,Code ("",["py","python","indirect","sourceCode"],[]) "[x*x for x in [1,2,3,4,5]]",Str "."]